烧结助剂对硼硅钙微晶玻璃结构和介电性能的影响

EFFECTS OF SINTERING ADDITIVES ON MICROSTRUCTURE AND DIELECTRIC PROPERTIES OF CALCIUM BOROSILICATE GLASS-CERAMICS

研究了烧结助剂P2O5和ZnO对CaO–B2O3–SiO2(CBS)玻璃粉末的助烧作用及其对材料的相组成、显微结构和介电性能的影响。结果表明:未添加烧结助剂在1000℃烧成的样品晶粒粗大(1～3μm),且结构疏松。复合添加2%(质量分数,下同)P2O5和0.5%ZnO后,850℃烧成的CBS微晶玻璃中,包含有β–CaSiO3,α–SiO2和CaB2O43种晶相,晶粒发育细小均匀,粒径为0.5μm左右,具有一定量的玻璃相,且结构致密。加烧结助剂制得的样品在10MHz下,相对介电常数εr为6.38,介电损耗tanδ为0.0018。加复合烧结助剂P2O5和ZnO有效地降低了CBS玻璃粉末的烧结温度(低于900℃),可实现银、铜电极共烧。烧结助剂的作用机理是P2O5促进了液相的生成,ZnO则具有提高液相的粘度,增大烧结温度范围,细化晶粒和防止样品变形的作用。

The effects of additives P2O5 and ZnO on the sintering process, phase composition, microstructures and dielectric properties of CaO-B2O3-SiO2 （CBS） glass-ceramics were investigated. The results show that without additives, the crystal grains of the samples sintered at 1000℃ are large, ranging from l to 3μm, and the structure is rough. With the combined additives of 2% （mass fraction, the same below） P2O5 and 0.5% ZnO, the crystal phases of the sample sintered at 850℃ are β-CaSiO3, a-SiO2 and CaB2O4, the grains are fine （around 0.5 pro） and uniformly distributed. Some glassy phase exists in the sample, and the structure is dense. The dielectric constant erand dielectric loss tan δ of the material obtained by adding the additives are 6.38 and 0.001 8 respectively at 10 MHz. The sintedng temperature of CBS glass powders can be lower than 900℃ with P2Os and ZnO additives, and co-firing with Ag and Cu is possible. The effect of the combined additives can be attributed to the following advantages of each additive： P2O5 can promote the formation of low melting point glass phase and lower the sintering temperature, and ZnO can improve the viscosity of low melting point glass, widen the sintering temperature range, make the crystal grains fine and prevent distortion of glass-ceramics.